1. Technical Field
This invention relates to diagnostic systems and, more particularly, to diagnostic systems incorporating interconnected virtual components which parallel components of a real system, which form a virtual model and which generate virtual output signals for point-to-point comparison with real system component outputs.
2. Discussion
Maintenance diagnostics for complex real systems, for example aircraft navigation, weapons release, engine control, etc. are becoming increasingly important as complexity and uniqueness of each real system increases. For example, an aircraft navigation system may include multiple line replaceable units and each line replaceable unit can contain multiple shop replaceable units.
Ideally, maintenance personnel would be able to service different aircraft types and aircraft systems for each aircraft type. However, in practice, conventional maintenance diagnostics have required maintenance personnel to have significant prior experience and background training thus decreasing a likelihood that one maintenance technician can work on multiple systems.
Conventional diagnostic systems rely heavily upon paper-based technical manuals, other manual procedures, and prior work experience of the technician. Conventional computer diagnostic systems typically automate the paper-based systems. Both conventional diagnostic systems implement rule-based approaches which rely upon a pre-defined body of knowledge stored in an internal database. Effectiveness of these diagnostic systems is related to accuracy of the pre-defined body of knowledge stored in the database, and technician work experience.
Under ideal conditions, a maintenance technician should have an exact duplicate or replica of a system under test. For example, when an aircraft is experiencing failures or malfunctions, a preferred diagnostic system would provide a duplicate operational aircraft running in parallel to the aircraft under test. The maintenance technician would then simply compare signal points to identify faulty components. However such a preferred diagnostic system is not feasible.
Therefore a need exists for a cost effective diagnostic system which relies less on prior work experience of the technician, is easily modifiable, allows one technician to readily work on multiple systems, and simply compares signal points to identify faulty hardware components and shop replaceable units.
A need also exists for a two-level diagnostic system including a first level in which faulty line replaceable units (LRUs) are identified so that the LRU can be removed quickly and replaced to allow the aircraft to return to active service immediately. Subsequently, a second level would identify shop replaceable units (SRUs) in the faulty LRU. The faulty SRU can be replaced and later the LRU can be returned to service. Diagnostics can continue until a faulty individual circuit component or group of components are identified on the faulty SRU.